Endothelial-dependent and independent vasodilatation: Brachial Artery Flow-Mediated Dilatation (FMD) of the brachial artery will be measured as a quantitative readout of NO-mediated conduit vessel endothelial function, as we have done in several previous studies and in accordance with international guidelines.Endothelial dependent (hyperaemic flow after cuff occlusion) and endothelial independent (GTN) responses of the brachial artery will be measured using high-resolution ultrasound imaging with automated vessel diameter measurements (Vascular Analyser, MIA Inc. Iowa). FMD and GTN induced dilatation will be measured as absolute and proportional changes in arterial diameter.Reproducibility data from our laboratory show a coefficient of variation for inter-study measurements of <10% comparable to other reports.